by Jeff Gluck, USA TODAY Sports

by Jeff Gluck, USA TODAY Sports

Nelson Piquet Jr. has been fined $10,000 and ordered to attend sensitivity training after posting an Instagram comment with a gay slur.

In response to fellow Nationwide Series driver Parker Kligerman's selfie after a workout, Piquet wrote a comment with a three-letter slur. Kligerman appeared to laugh it off with a comment of his own, but a fan snapped a screen shot and it caught NASCAR's attention.

In a Twitter exchange with @MatthewBreuer, Piquet said the comment was teasing between friends.

"Don't act like if u have never called your friends names," Piquet said in a now-deleted tweet. "Were (sic) not living in the 50s anymore bud.. jokes are jokes."

In a statement Tuesday, Piquet said: "I sincerely apologize to everyone for my poor choice of words last week. I did not mean to hurt or offend anyone. This has been a cultural learning experience that will make me a more sensitive person moving forward."

Kligerman didn't immediately respond to a request for comment from USA TODAY Sports.

Piquet also was placed on indefinite probation.

Earlier this season, Nationwide driver Jeremy Clements was suspended for two races after he made a racial slur toward African-Americans.

"Nelson Piquet Jr. recently communicated an offensive and derogatory term that cannot be tolerated in our sport," NASCAR senior vice president of racing operations Steve O'Donnell said. "NASCAR's Code of Conduct explicitly spells out in the 2013 rule book our position regarding the use of disparaging terms. We expect our entire industry to abide by this code."

The Code of Conduct in the rule book says a driver "shall not make or cause to be made a public statement and/or communication that criticizes, ridicules or otherwise disparages another person based upon that person's race, color, creed, national origin, gender, sexual orientation, marital status, religion, age, or handicapping condition.''

In a separate statement from Turner Scott Motorsports, the team said it had spoken to Piquet about his "insensitive comment" and the driver "understands that such remarks will not be tolerated."

"TSM expects those associated with the team to uphold professional standards that we can all be proud of," the statement said. "Nelson has assured the team that he has learned his lesson and he knows what it means to represent TSM."

This isn't the first time Piquet has found controversy in 2013.

After on-track fireworks in May's Nationwide race at Richmond International Raceway, the ex-Formula One driver argued with Brian Scott and kicked him below the belt.

On the way out of the track, Piquet and a friend were then confronted by two crew members from Scott's Richard Childress Racing team. The crew members were arrested and charged with assault.